The Obama administration is boasting that 8 million Americans, including a good number of young people, have enrolled in public exchange plans. The big question now is how will new members fit into the risk adjustment puzzle?

Aside from collecting premiums — it’s still not known how many of the new enrollees have paid for the first month — many exchange insurers are now trying to learn as much as they can about new enrollees to start assigning them risk scores.

What is known is that in the 36 states with federally-managed exchanges, 28 percent of new plan buyers are between 18 and 34 years old — a bit less perhaps than what some may have hoped for, but probably enough to avert a premium “death spiral.”